Howell was joined at 12-under-par 132 by Nick Dougherty, who shot 68 in round two. Dougherty shared the first-round lead with 1999 British Open champion Paul Lawrie and Peter O'Malley.
Paul Casey, Thaworn Wiratchant and Lian-Wei Zhang each notched rounds of 4-under 68 to get to minus-9. They were joined in fifth place by Robert-Jan Derksen (70) and Kenneth Ferrie (69). Ferrie had the early lead on the front nine thanks to a hole-in-one at the par-3 sixth, but four bogeys over his last 11 holes dropped him down the leaderboard.
Woods birdied No. 2 for the second straight day. After parring his next four holes, the top player in the world bogeyed the seventh to slip back to 7-under.
The 29-year-old rolled in a 10-foot birdie putt at the ninth. Woods sank a six-foot birdie effort at the 13th. He came right back to birdie No. 14.
Woods then ran in a 10-foot birdie putt at 15 to climb to 11-under. He missed the fairway at the short par-4 16th and was unable to save par. Woods was in trouble again on 18 after finding water with his second, but he sank a long par putt to close at 10-under.
'I am a little bit frustrated,' Woods said. 'I didn't really get going today. If not for that last putt, I would have been 2-over for the last three holes and that would have left a bad taste in my mouth.'
Howell converted his first birdie on the par-5 second. He climbed to 9-under thanks to a birdie on the fifth.
The Englishman drained a seven-foot birdie attempt on the par-5 eighth to make the turn at minus-10. Howell ran off five straight pars around the turn.
Howell kicked in a four-foot birdie try on the 14th to get to 11-under and a share of the lead with Ferrie. Howell got to 12-under thanks to a five-foot birdie putt at the par-5 closing hole.
'We could just do with some nice weather and everything would be great,' said Howell of the wet conditions players have faced the first two days. 'I'm really pleased to get round without a bogey.'
Dougherty, who played the back nine first on Saturday, sank his first birdie on the par-four 11th. He birdied the 14th to get to 10-under. After five pars around the turn, he birdied the second.
The 23-year-old stumbled to a three-putt bogey at the next, however. Dougherty climbed back to 11-under and a share of the lead with a birdie at four. He drained a 25-footer for birdie on the fifth to move to 12-under. Dougherty parred his final four holes to share the second-round lead.
World No. 2 Vijay Singh matched Woods' 69 to climb to 8-under-par 136. He was joined in a tie for 10th place by K.J. Choi (71), U.S. Open champion Michael Campbell (70), O'Malley (72) and Ian Poulter (69).
Lawrie stumbled to a 3-over 75 and shares 19th at minus-5.